Boys with suspected ADHD are typically more likely to be referred for clinical evaluation than girls. This might be because boys with ADHD appear to show more disruptive and externalising behaviour than girls with ADHD (Gaub and Carlson, 1997), and it is believed that this may leave many school-age and adolescent girls with ADHD undiagnosed. This retrospective, observational, Italian study aimed to describe the clinical characteristics of children and adolescents diagnosed with ADHD, and to provide a better understanding of the symptoms shown by boys and girls upon ADHD diagnosis.

Children and adolescents referred for ADHD evaluation between January 2018 and December 2020 who attended the Child and Adolescent Neuropsychiatry Unit of the Bambino Gesù Children’s Hospital (Rome, Italy) were included in this study. Participants were not receiving any ADHD medication and were excluded if they showed any comorbidities, including autism spectrum disorder and intellectual disability. Diagnoses of ADHD were made by developmental psychiatrists and neuropsychologists, and clinical characteristics of ADHD were assessed, including global functioning, IQ, adaptive skills, symptom severity (Conners’ Parent Rating Scale-Revised Long Version [CPRS-R:L]*), and behaviour and emotions of the children (Child Behaviour Checklist for Ages 6–18 [CBCL/6–18]^†).

A total of 715 children and adolescents (108 females) were included in this study, and the mean (standard deviation [SD]) age of all participants was 9.4 (2.9) years. No difference was observed between males and females in global functioning and adaptive skills. However, males showed a higher mean (SD) IQ compared with females (105.34 [18.00] vs 100.71 [20.36]; t₅₄₇=2.08; p=0.03). All participants showed higher mean (SD) scores on the ADHD index (78.23 [0.82]) compared with all other CPRS-R:L subscales (p<0.001). However, the Diagnostic and Statistical Manual of Mental Disorders – 4th Edition (DSM-IV) hyperactive/impulsive subscale showed higher mean (SD) scores (76.69 [0.88]) than other subscales. In both cases, the mean scores passed the clinically relevant threshold of 70 on the CPRS-R:L and the higher scores were seen in females. In terms of behaviour and emotions (CBCL/6–18), children were seen to have high mean (SD) scores in (among others) attention (68.47 [9.44]), affective (64.98 [9.00]), social (64.18 [8.52]), anxiety (64.05 [7.89]), internalising (62.48 [9.65]) and oppositional-defiant (63.29 [ 8.44]) problems. This analysis highlighted that males scored higher than females in several subscales, such as withdrawn/depressed (mean [SD], 62.14 [9.51]), internalising and obsessive-compulsive (mean [SD], 61.70 [9.87]) problems.

The researchers believed that their findings may be limited by the characteristics of the girls involved in the study. This is because the girls referred to the clinic were more likely to be the ones showing severe symptoms of ADHD, as opposed to girls that might show milder symptoms and hence not be referred for evaluation, thus potentially resulting in selection bias. It was also noted that parents involved in the study may have had undiagnosed persistent adult ADHD, which should be considered when interpreting the results.

The researchers concluded that, in this study, girls showed more severe ADHD symptoms and lower IQ, whereas boys showed more internalising problems and obsessive-compulsive symptoms. It was suggested that these findings could be a starting point in better defining the differences in ADHD symptoms between boys and girls, and their impact on the response to medication following-up on the initial diagnosis.

Read more about gender-related differences in ADHD here

*CPRS-R is a clinical tool for obtaining parental reports of childhood behaviour problems by scoring 57 items divided into factors, which include cognitive, oppositional and social problems, hyperactivity/impulsivity, anxious/shy behaviour, perfectionism and psychosomatic characteristics (Conners et al, 1998)
^†CBCL (6–18) is completed by parents and is a questionnaire on child and adolescent behaviours and emotions (Volkmar, 2011)

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